/* @LICENSE(MUSLC_MIT) */

/* origin: FreeBSD /usr/src/lib/msun/src/s_remquof.c */
/*-
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunSoft, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */
/*
 * Return the IEEE remainder and set *quo to the last n bits of the
 * quotient, rounded to the nearest integer.  We choose n=31 because
 * we wind up computing all the integer bits of the quotient anyway as
 * a side-effect of computing the remainder by the shift and subtract
 * method.  In practice, this is far more bits than are needed to use
 * remquo in reduction algorithms.
 */

#include "libm.h"

static const float Zero[] = {0.0, -0.0,};

float remquof(float x, float y, int *quo)
{
	int32_t n,hx,hy,hz,ix,iy,sx,i;
	uint32_t q,sxy;

	GET_FLOAT_WORD(hx, x);
	GET_FLOAT_WORD(hy, y);
	sxy = (hx ^ hy) & 0x80000000;
	sx = hx & 0x80000000;   /* sign of x */
	hx ^= sx;               /* |x| */
	hy &= 0x7fffffff;       /* |y| */

	/* purge off exception values */
	if (hy == 0 || hx >= 0x7f800000 || hy > 0x7f800000) /* y=0,NaN;or x not finite */
		return (x*y)/(x*y);
	if (hx < hy) {       /* |x| < |y| return x or x-y */
		q = 0;
		goto fixup;
	} else if(hx==hy) {  /* |x| = |y| return x*0*/
		*quo = sxy ? -1 : 1;
		return Zero[(uint32_t)sx>>31];
	}

	/* determine ix = ilogb(x) */
	if (hx < 0x00800000) {  /* subnormal x */
		for (ix = -126, i=hx<<8; i>0; i<<=1) ix--;
	} else
		ix = (hx>>23) - 127;

	/* determine iy = ilogb(y) */
	if (hy < 0x00800000) {  /* subnormal y */
		for (iy = -126, i=hy<<8; i>0; i<<=1) iy--;
	} else
		iy = (hy>>23) - 127;

	/* set up {hx,lx}, {hy,ly} and align y to x */
	if (ix >= -126)
		hx = 0x00800000|(0x007fffff&hx);
	else {  /* subnormal x, shift x to normal */
		n = -126 - ix;
		hx <<= n;
	}
	if (iy >= -126)
		hy = 0x00800000|(0x007fffff&hy);
	else {  /* subnormal y, shift y to normal */
		n = -126 - iy;
		hy <<= n;
	}

	/* fix point fmod */
	n = ix - iy;
	q = 0;
	while (n--) {
		hz = hx - hy;
		if (hz < 0)
			hx = hx << 1;
		else {
			hx = hz << 1;
			q++;
		}
		q <<= 1;
	}
	hz = hx - hy;
	if (hz >= 0) {
		hx = hz;
		q++;
	}

	/* convert back to floating value and restore the sign */
	if (hx == 0) {                             /* return sign(x)*0 */
		q &= 0x7fffffff;
		*quo = sxy ? -q : q;
		return Zero[(uint32_t)sx>>31];
	}
	while (hx < 0x00800000) {  /* normalize x */
		hx <<= 1;
		iy--;
	}
	if (iy >= -126) {          /* normalize output */
		hx = (hx-0x00800000)|((iy+127)<<23);
	} else {                   /* subnormal output */
		n = -126 - iy;
		hx >>= n;
	}
fixup:
	SET_FLOAT_WORD(x,hx);
	y = fabsf(y);
	if (y < 0x1p-125f) {
		if (x + x > y || (x + x == y && (q & 1))) {
			q++;
			x -= y;
		}
	} else if (x > 0.5f*y || (x == 0.5f*y && (q & 1))) {
		q++;
		x -= y;
	}
	GET_FLOAT_WORD(hx, x);
	SET_FLOAT_WORD(x, hx ^ sx);
	q &= 0x7fffffff;
	*quo = sxy ? -q : q;
	return x;
}
